Radon Gas: What It Is And How It Affects Your Health

Radon gas is a silent health risk found in homes and buildings across the UK. It is a naturally occurring radioactive gas that comes from uranium in soil and rocks. You can’t see, smell, or taste it, making it nearly impossible to detect without proper testing. Radon seeps into buildings through small cracks and gaps in floors, walls, and foundations. Once trapped indoors, it can build up to unsafe levels over time, especially in spaces with poor airflow.

Long-term exposure to high radon levels increases the risk of lung cancer. In fact, radon is the second biggest cause of lung cancer in the UK after smoking. This risk is even greater for smokers, as the combined effect is much more dangerous. Despite its serious health impact, radon often goes unnoticed due to lack of awareness. The UK Health Security Agency recommends testing for radon in affected areas to stay safe.

Testing is affordable, easy to carry out at home, and essential for peace of mind. Many building materials suppliers now offer radon protection products, including test kits and gas membranes, to help homeowners and contractors manage this hidden threat. In this article, we’ll explain what radon gas is, how it enters your home, and the simple steps you can take to reduce exposure and protect your health.

Understanding Radon Gas: What It Is and Why You Should Care

What Is Radon?

Radon is a radioactive gas that you cannot see, smell, taste, or feel. It forms naturally underground when uranium, a metal found in soil and rocks, begins to break down. This process turns uranium into another metal called radium, which then decays into radon gas. Once released, radon can escape from the ground and enter the air and water around us.

In open outdoor spaces, radon levels are usually low and not harmful. The problem begins when radon seeps into enclosed buildings, such as homes and workplaces. It enters through cracks in floors, gaps around pipes, or poorly sealed foundations. Once inside, radon can build up to unsafe levels, especially in basements or rooms with limited airflow.

Although radon is a natural gas, long-term exposure to high levels can pose serious health risks. Breathing it in regularly over many years can damage lung tissue and increase the risk of lung cancer. Thankfully, reliable testing methods are available to help monitor and manage exposure. Taking preventive action early is the best way to reduce your risk and protect your health.

Risks of Radon Exposure

When you breathe in radon gas, it enters your lungs and exposes the lining to small doses of radiation. Over time, this radiation can damage lung cells, increasing your risk of lung cancer. Radon is now recognised as the second leading cause of lung cancer in the UK, just after smoking.

The risk becomes even higher for people who smoke and live in homes with elevated radon levels. The combined effect of tobacco and radon exposure creates a much greater cancer risk than either on its own. According to global health data, around 21,000 lung cancer deaths are linked to radon exposure each year.

Some studies also suggest radon may be linked to other cancers, such as childhood leukaemia, though the evidence remains limited. Children may be more vulnerable to radon due to their faster breathing rate and smaller lung capacity. These factors mean that children can inhale more radon per body weight than adults. While experts are still studying the full impact, some believe children could face twice the risk of lung cancer compared to adults exposed to the same amount.

Understanding these risks is key to protecting your family, especially if you live in a radon-prone area. Early testing and ventilation improvements are simple but powerful ways to reduce these long-term dangers.

Symptoms of Radon Exposure

Radon exposure does not cause any immediate symptoms. You won’t feel sick or notice anything unusual right away. Health problems often take years to develop, with lung cancer being the most serious long-term effect.

Since there are no early signs of radon poisoning, it's important to watch for symptoms linked to lung issues. These may appear slowly and become more noticeable over time. 

Some of the common warning signs include:

• A persistent cough that doesn’t go away

• Shortness of breath or wheezing

• Coughing up blood

• Chest pain or discomfort

• Unexplained weight loss

If you notice any of these symptoms, speak to your GP immediately. They may suggest further checks or refer you to a specialist.

There are no routine tests to confirm how much radon you’ve breathed in. Doctors cannot remove radon from your body once it’s inhaled. However, if you think you’ve been exposed for a long time, your doctor may order tests to monitor your lung health.

Acting early and knowing the signs can make a big difference. Prevention and awareness are your best defence against long-term harm.

Where Is Radon Found?

Radon gas is found almost everywhere, but some areas have much higher levels than others. It naturally escapes from the ground and enters the air. Certain conditions increase the chances of radon building up in a home or building.

High radon levels are more likely in areas with uranium-rich rocks underground. These include granite, limestone, and shale, as well as land with coal seams or fractured bedrock. Cavern systems beneath the surface, especially limestone ones, can also release more radon into the air.

Soil type plays a major role as well. Some soils allow radon to move through them more easily, especially if they are loose or dry. 

You are more likely to find higher radon levels in areas with:

• Dry soil that rarely retains moisture

• Soil that cracks when it dries out

• Sloped or hilly terrain

• Thin soil where the bedrock lies close to the surface

• Ground made of loose gravel or sand

In the UK, some of the highest radon levels have been found in the South West, particularly in Cornwall and Devon. But that doesn't mean other areas are safe. Radon levels can vary from one street—or even one house—to another.

Health and safety experts recommend testing your home regardless of location. Even if your region has low average readings, your property could still be at risk. Testing is the only reliable way to know your home’s radon level.

How Are You Exposed to Radon?

Radon enters buildings from the ground below. Since homes, schools, and offices are built on soil or rock, radon can easily rise indoors. It moves through cracks in floors, gaps in walls, and poorly sealed spaces around pipes and wiring. Once inside, radon can become trapped, especially in rooms that lack ventilation.

Basements and crawl spaces are at higher risk because they sit closest to the soil. Without regular airflow, these spaces can collect more radon than upper floors. Even well-built homes can allow radon to enter if small openings are present.

Although indoor air is the main way people are exposed, other sources may contribute. Some materials used in buildings can release small amounts of radon over time. 

These include:

• Concrete and cement-based blocks

• Plasterboard or wallboard made from natural gypsum

• Natural stone surfaces, such as granite countertops

These materials usually release very low levels of radon. On their own, they are not considered a major risk. However, in poorly ventilated homes, they could slightly increase total exposure.

Occupational exposure is another factor. People who work underground—like miners—or handle phosphate-based fertilisers may face higher risks. Employers in such industries are advised to follow health and safety guidelines to reduce radon exposure in the workplace.

Radon can also be found in water, especially from underground sources like private wells. Water from surface sources—like rivers and reservoirs—usually releases radon into the air before reaching homes. However, groundwater can carry more radon into indoor air during activities like showering, cooking, or washing.

Understanding how radon enters your environment is the first step to managing the risks. Testing and proper ventilation are simple but effective ways to reduce exposure.

How Do You Test Your Home for Radon?

Testing your home for radon is a simple but important step to protect your long-term health. Radon is invisible and odourless, so testing is the only way to know if your home has a problem. In the UK, radon levels are measured in becquerels per cubic metre (Bq/m³). According to the UK Health Security Agency (UKHSA), 200 Bq/m³ is the level at which you should take action to reduce radon.

Most homes have radon levels below this threshold, but some can exceed it significantly—especially in high-risk areas. Even if you live in a lower-risk postcode, there’s no guarantee your home is safe. Radon can vary from one property to another, even on the same street. That’s why testing is recommended for all households, particularly if you spend a lot of time indoors or have a basement.

Step 1: Get a Radon Test Kit

You can purchase a radon test kit easily in the UK. They are available from:

• The UK Radon Association

• UKHSA’s Radon Services

• Accredited private testing companies

• Some local authorities in radon-affected areas, which may offer discounts or free kits

These kits are small, unobtrusive devices that detect radon over time. Most UK homes use long-term detectors, which are more reliable than short-term ones. A long-term test lasts for three months, providing a clearer picture of your home’s typical radon exposure.

Step 2: Place the Kit Correctly

Once you receive your kit, follow the instructions carefully. Correct placement is essential for accurate readings. 

For best results, you should:

• Place the detector in the lowest lived-in level of your home, such as a basement or ground floor

• Keep it in a central location, away from direct sunlight, heaters, windows, or external walls

• Avoid placing it in kitchens, bathrooms, or laundry areas, as moisture and steam can affect accuracy

You may need to place multiple detectors in larger homes or buildings with more than one floor.

Step 3: Let the Test Run

After placing the detector, leave it undisturbed for the full test period. 

During this time:

• Keep windows and external doors closed as much as possible

• Maintain normal living conditions—don’t change how you use the room

• Make sure the detector stays in place and isn’t moved or tampered with

At the end of the testing period, post the detector back to the lab using the pre-paid envelope. You’ll receive your results by email or post, usually within a couple of weeks.

Understanding Your Results

• Below 100 Bq/m³ – No action needed; your home is low risk

• 100–200 Bq/m³ – Consider action; levels are higher than average

• Above 200 Bq/m³ – Action is recommended; steps should be taken to reduce radon exposure

If your results are borderline or high, consider conducting a second test to confirm the reading. Long-term results are more accurate than short-term ones, especially in homes where radon levels change with the seasons.

Professional Help and Next Steps

If you’re unsure about testing yourself, you can hire a qualified radon specialist to carry out the test and advise on next steps. The UK Radon Association provides a directory of professionals across the country.

Testing is low-cost, easy, and could help you avoid serious health issues down the line. By testing now, you can make informed choices to protect your home and family from long-term radon exposure.

How to Reduce Radon Levels

You can reduce radon levels in any type of property, regardless of location or building style. Effective systems work quickly and reliably, and can often be installed within a single day by qualified contractors.

In the UK, two main approaches are used: preventative measures for new builds and mitigation systems for existing homes. Both are designed to bring indoor radon levels below the UK Health Security Agency’s recommended action level of 200 Bq/m³.

Radon Barriers in New Homes

For new homes and extensions, radon barrier membranes are one of the most common preventative methods. These gas-resistant layers are installed beneath the floor during construction. They stop radon from entering the building by forming a sealed barrier between the ground and the internal air. In high-radon areas, Building Regulations require these systems to be installed during construction.

These membranes are often paired with ventilation layers or sump systems to provide further protection. When correctly fitted, they offer long-term control with little to no maintenance.

Active Soil Depressurisation (ASD) in Existing Homes

For homes already built, the most effective system is called Active Soil Depressurisation (ASD)—also known as a radon sump system. This technique works by drawing radon gas from under the house and venting it safely outside before it enters the property.

A pipe is inserted into the ground beneath your home, and a small fan is connected to create a constant vacuum. This setup lowers the pressure below the building, preventing radon from being drawn indoors.

The exact installation depends on your home’s structure:

• Solid floors (slab foundations): A small hole is drilled into the slab to insert the pipe.

• Crawl spaces: The soil is covered with a thick plastic membrane sealed to the foundation. A fan then extracts the radon from beneath it.

Both methods are discreet and highly efficient in reducing radon levels to a safe range.

Supporting Measures to Improve Results

In addition to the main system, contractors will seal up other radon entry points, including:

• Cracks in floors or walls

• Gaps around pipes and electrical conduits

• Openings in foundations or floor joints

Sealing helps reduce radon entry and boosts the system's overall performance. Natural ventilation, such as opening windows or vents, can also help—though only temporarily. Once closed, radon levels tend to return to previous levels within 12 hours.

Monitoring and Maintenance

After installation, your radon system should be tested every two years to ensure it’s still working effectively. The fan system should also be checked regularly. Most fans last between 5 to 15 years before needing repair or replacement.

Many systems include a built-in warning device to alert you if the fan stops working. These fans must remain on at all times and typically use no more electricity than a small household lightbulb.

Cost of Radon Reduction in the UK

The cost to reduce radon levels varies depending on several factors:

• The size and layout of your home

• The type of foundation or floor construction

• Building Materials used in your home

• Local labour rates and accessibility

Radon reduction systems in the UK must meet standards set by relevant environmental and building regulations. Installation should be carried out by qualified professionals who follow best practices for safety and efficiency. Most systems include a manufacturer’s warranty and are designed to operate with minimal energy use.

Reducing radon levels is recognised as an important step in protecting public health and indoor air quality. Regular testing, professional installation, and proper maintenance ensure your home stays within recommended safety limits. Taking these measures provides long-term reassurance and supports a healthier living environment.

Conclusion

Radon is a silent but serious health hazard that can exist in any home, regardless of where you live. It enters buildings unnoticed and can slowly build up over time, leading to long-term health issues such as lung cancer. Because it has no smell, colour, or taste, you won’t know it’s there unless you test for it.

The good news is that you can take simple, effective steps to stay safe. Testing is quick, low-cost, and widely available. It’s the only way to accurately measure radon levels in your property. If levels are high, proven solutions like radon sump systems or improved ventilation can significantly reduce the danger.

New-build homes in radon-affected areas can be protected through radon barrier membranes, as required by Building Regulations. Older homes can also be upgraded with mitigation systems to improve air safety. Regular testing, professional guidance, and prompt action are the best ways to protect your health and home environment.

Don’t wait until health symptoms appear. Be proactive. Start by testing your home for radon and take control of your indoor air quality today.

Frequently Asked Questions (FAQs)

Can I detect radon by smell or sight?

No. Radon is invisible, odourless, and tasteless. Only a radon test can confirm if it's present.

How often should I test my home for radon?

Test your home every two years, or after any major building work or renovations.

What radon level is considered unsafe in the UK?

The UK action level is 200 becquerels per cubic metre (Bq/m³). Any reading above this requires action.

Do new homes need radon protection?

Yes. In high-risk areas, UK Building Regulations require radon-resistant barriers during construction.

Are radon mitigation systems expensive to run?

No. Most systems are energy-efficient and cost little to run—similar to leaving a small light bulb on.